When Katie Spotz launched her boat off the coast of Senegal, West Africa, the open seas seemed welcoming. It was January 3, 2010, and she had more than 2,500 miles ahead in her attempt to become the youngest person to row solo across the Atlantic Ocean and raise awareness for her cause: clean drinking water. Three weeks in, dolphins surrounded her boat, chirping happily as she petted their rubbery skin.

But every day meant 10,000 strokes, causing painful abrasions on her skin. The sea, anything but calm, tossed the craft so violently she couldn't sleep more than two hours a night. "I felt so stiff and sore, I just wanted to cry," Spotz recalls. Midway through her trip, her nerves were so raw that little things—like a water leak that ruined a precious stash of Twix bars—felt like epic disasters. She even thought she saw ghost ships on the horizon. To calm herself along the way, Spotz recited a simple mantra: "Just focus on what's in your control."

It was that advice that saved her during her last, biggest test: Two days away from her goal—French Guiana, in South America—vicious trade winds that roiled the water prevented her from reaching shore. But Spotz refused to be towed to her destination, and instead detoured 400 miles into calmer seas, adding eight days to her trip. By the time she made land on March 14, she could barely walk. But it was worth it: Spotz's journey raised money for Blue Planet Network, which buys water purifiers and digs wells in Haiti, India and Kenya. "My hope," Spotz says, "is to make people realize they're capable of so much more than they think."